Transmission issue — 2021 Yukon XL broke down 5/6/25 while driving with 2 of our children in the vehicle. the RPMs skyrocketed but the vehicle wouldn’t go. was hard shifting and speed would not exceed 35ish MPH. message popped up on vehicle that said acceleration throttled and engine light came on. Took it to dealership and it is a known problem. Transmission needs a valve body replacement. This part is on national backorder for months. Spoke with the dealership on 6/5/25 and they still do not have an ETA. They ordered one on 3/19/25 that still has not arrived. I received a case number from GM but they are extremely unhelpful.